A computer controlled 3-D positioning system is developed for acquiring B-mode ultrasonic images with single element transducers. The system has a resolution of better than 5 fm and a scanning speed to allow acquiring at least 5 frames of images in one second with an excursion range of 1 cm. Once completed, the performance of the system will be assessed on excised rabbit eyes and on patients at Hershey Medical Center with the assistance of the physicians.